My screwball project to see where to throw the pitch and how to utilize it.

Screwball project.R

library(ggplot2)
library(tidyverse)
library(mgcv)
library(viridis)
library(dplyr)
library(MASS)


# Dataframes ###########################################################

scb.right = filter(screwball_data, stand == 'R')
scb.left = filter(screwball_data, stand == 'L')
scb.p.right = filter(screwball_data, p_throws == 'R')
scb.p.left = filter(screwball_data, p_throws == 'L')


r.whiff = filter(scb.right, description == c('swinging_strike', 'swinging_strike_blocked'))
l.whiff = filter(scb.left, description == c('swinging_strike', 'swinging_strike_blocked'))
whiff = filter(screwball_data, description == c('swinging_strike', 'swinging_strike_blocked'))

screwball_data$wOBA = ifelse(screwball_data$events == 'walk', .69, NA)
screwball_data$wOBA = ifelse(screwball_data$events == 'single', .89, screwball_data$wOBA)
screwball_data$wOBA = ifelse(screwball_data$events == 'double', 1.27, screwball_data$wOBA)
screwball_data$wOBA = ifelse(screwball_data$events == 'triple', 1.62, screwball_data$wOBA)
screwball_data$wOBA = ifelse(screwball_data$events == 'home_run', 2.10, screwball_data$wOBA)
screwball_data$wOBA = ifelse(screwball_data$description == 'hit_into_play', 0, screwball_data$wOBA)
screwball_data$wOBA = ifelse(screwball_data$events == 'strikeout', 0, screwball_data$wOBA)

sc.woba = screwball_data[,c('wOBA', 'plate_x', 'plate_z')]
sc.woba = arrange(sc.woba, by = wOBA)
sc.woba = sc.woba[c(1:254),]

######################################################################






# Location Heatmaps (help from Boyd) ###################################################

ggplot(scb.left, aes(plate_x, plate_z)) +
  stat_density_2d(geom = 'polygon', aes(fill=..level..))+
  scale_fill_viridis(option='C') +
  geom_segment(x=-0.7, xend=0.7, y=1.5, yend=1.5, col = "red") +
  geom_segment(x=-0.7, xend=0.7, y=3.5, yend=3.5, col = "red") +
  geom_segment(x=-0.7, xend=-0.7, y=1.5, yend=3.5, col = "red") +
  geom_segment(x=0.7, xend=0.7, y=1.5, yend=3.5, col = "red") +
  ylim(0,4) +
  xlim(-2,2) +
  coord_fixed() +
  theme_bw() +
  xlab('Horizontal Location') +
  ylab('Vertical Location') +
  ggtitle('Screwball Location on LHB') +
  guides(fill = guide_legend(title = 'Location %'))

ggplot(scb.right, aes(plate_x, plate_z)) +
  stat_density_2d(geom = 'polygon', aes(fill=..level..))+
  scale_fill_viridis(option='C') +
  geom_segment(x=-0.7, xend=0.7, y=1.5, yend=1.5, col = "red") +
  geom_segment(x=-0.7, xend=0.7, y=3.5, yend=3.5, col = "red") +
  geom_segment(x=-0.7, xend=-0.7, y=1.5, yend=3.5, col = "red") +
  geom_segment(x=0.7, xend=0.7, y=1.5, yend=3.5, col = "red") +
  ylim(0,4) +
  xlim(-2,2) +
  coord_fixed() +
  theme_bw() +
  xlab('Horizontal Location') +
  ylab('Vertical Location') +
  ggtitle('Screwball Location on RHB') +
  guides(fill = guide_legend(title = 'Location %'))

#################################################################







# Finding strike percentage #############################

screwball_data = screwball_data %>%
  mutate(s.b = ifelse(launch_speed == 'null', 1, 0))

k.b = screwball_data %>%
  filter(s.b == 1)

k.b = k.b %>%
  mutate(sk = ifelse(type == 'S', 1, 0))

k.b = k.b %>%
  mutate(b = ifelse(type == 'B', 1, 0))

totk = sum(k.b$sk)
totb = sum(k.b$b)
tot = sum(k.b$s.b)

k. = totk / tot   # 39.3%

#######################################################







# L vs R ############################################################
left = screwball_data %>%
  filter(stand == 'L', p_throws == 'L')
leftwOBA = left %>%
  filter(woba_value != 'null')
leftwOBA$woba_value <- as.numeric(as.character(leftwOBA$woba_value))
mean(leftwOBA$woba_value)

right = screwball_data %>%
  filter(stand == 'R', p_throws == 'L')
rightwOBA = right %>%
  filter(woba_value != 'null')
rightwOBA$woba_value <- as.numeric(as.character(rightwOBA$woba_value))
mean(rightwOBA$woba_value)


leftR = screwball_data %>%
  filter(stand == 'L', p_throws == 'R')
leftRwOBA = leftR %>%
  filter(woba_value != 'null')
leftRwOBA$woba_value <- as.numeric(as.character(leftRwOBA$woba_value))
mean(leftRwOBA$woba_value)

rightR = screwball_data %>%
  filter(stand == 'R', p_throws == 'R')
rightRwOBA = rightR %>%
  filter(woba_value != 'null')
rightRwOBA$woba_value <- as.numeric(as.character(rightRwOBA$woba_value))
mean(rightRwOBA$woba_value)
#####################################################################







# Whiff heatmaps #######################################################

ggplot(r.whiff, aes(plate_x, plate_z)) +
  stat_density_2d(geom = 'polygon', aes(fill=..level..))+
  scale_fill_viridis(option='C') +
  geom_segment(x=-0.7, xend=0.7, y=1.5, yend=1.5, col = "red") +
  geom_segment(x=-0.7, xend=0.7, y=3.5, yend=3.5, col = "red") +
  geom_segment(x=-0.7, xend=-0.7, y=1.5, yend=3.5, col = "red") +
  geom_segment(x=0.7, xend=0.7, y=1.5, yend=3.5, col = "red") +
  ylim(0,4) +
  xlim(-2,2) +
  coord_fixed() +
  theme_bw() +
  xlab('Horizontal Location') +
  ylab('Vertical Location') +
  ggtitle('Screwball Location on RHB Whiffs') +
  guides(fill = guide_legend(title = 'Location %')) 

ggplot(l.whiff, aes(plate_x, plate_z)) +
  stat_density_2d(geom = 'polygon', aes(fill=..level..))+
  scale_fill_viridis(option='C') +
  geom_segment(x=-0.7, xend=0.7, y=1.5, yend=1.5, col = "red") +
  geom_segment(x=-0.7, xend=0.7, y=3.5, yend=3.5, col = "red") +
  geom_segment(x=-0.7, xend=-0.7, y=1.5, yend=3.5, col = "red") +
  geom_segment(x=0.7, xend=0.7, y=1.5, yend=3.5, col = "red") +
  ylim(0,4) +
  xlim(-2,2) +
  coord_fixed() +
  theme_bw() +
  xlab('Horizontal Location') +
  ylab('Vertical Location') +
  ggtitle('Screwball Location on LHB Whiffs') +
  guides(fill = guide_legend(title = 'Location %'))

###############################################################






# wOBA heatmaps (help from Weisberg and Caravan) ##################################################


gam_mod = mgcv::gam(wOBA ~ s(plate_x, plate_z),  
                    data = sc.woba)

grid = expand.grid(plate_x = seq(-2, 2, .1),  
                   plate_z = seq(0, 5, .1))

grid$xwOBA = predict(gam_mod, grid)  
ggplot(grid, aes(plate_x, plate_z)) +
  geom_tile(aes(fill = xwOBA)) +
  guides(fill = guide_legend(title = 'Expected wOBA')) + 
  xlab('Plate Side') +
  ylab('Plate Height') +
  geom_segment(x=-0.7, xend=0.7, y=1.5, yend=1.5, col = "red") +
  geom_segment(x=-0.7, xend=0.7, y=3.5, yend=3.5, col = "red") +
  geom_segment(x=-0.7, xend=-0.7, y=1.5, yend=3.5, col = "red") +
  geom_segment(x=0.7, xend=0.7, y=1.5, yend=3.5, col = "red") +
  coord_fixed()